WASHINGTON - President Donald Trump said Sunday that four minority, liberal congresswomen who have been critical of House Speaker Nancy Pelosi should “go back and help fix the totally broken and crime infested places from which they came,” prompting other Democrats - including Pelosi - to leap to their defense.

Pelosi, D-Calif., denounced Trump's tweets as "xenophobic comments meant to divide our nation," while the four congresswomen promised to continue fighting Trump's agenda and accused him of trying to appeal to white nationalists.

Trump's remark swiftly united a House Democratic caucus that had been torn apart in recent days by infighting between Pelosi and the four freshman women of color - Democratic Reps. Ayanna Pressley of Massachusetts, Rashida Tlaib of Michigan, Alexandria Ocasio-Cortez of New York and Ilhan Omar of Minnesota. It also comes after Trump announced that U.S. Immigration and Customs Enforcement officers were preparing to round up migrant families that have received deportation orders across the country.

Trump kicked off the furor with a string of tweets before heading to his golf club in Sterling, Virginia, on Sunday morning.

"So interesting to see 'Progressive' Democrat Congresswomen, who originally came from countries whose governments are a complete and total catastrophe, the worst, most corrupt and inept anywhere in the world (if they even have a functioning government at all), now loudly and viciously telling the people of the United States, the greatest and most powerful Nation on earth, how our government is to be run," Trump tweeted.

Pressley was born in Cincinnati, Tlaib was born in Detroit and Ocasio-Cortez was born in New York - about 20 miles from where Trump was born. Omar was born in Mogadishu, Somalia; her family fled the country amid civil war when she was a child, and she became a U.S. citizen as a teenager.

All four women won election to Congress in 2018.

"Why don't they go back and help fix the totally broken and crime infested places from which they came," Trump continued in the tweets. "Then come back and show us how it is done. These places need your help badly, you can't leave fast enough. I'm sure that Nancy Pelosi would be very happy to quickly work out free travel arrangements!"

Trump's comments prompted a sharp response from Pelosi, who described them as racist and divisive.

"When @realDonaldTrump tells four American Congresswomen to go back to their countries, he reaffirms his plan to 'Make America Great Again' has always been about making America white again," she said in a tweet. "Our diversity is our strength and our unity is our power."

The four freshmen lawmakers also fired back at Trump on Twitter. Omar wrote that "As Members of Congress, the only country we swear an oath to is the United States."

Pressley said in a statement that "it should come as no surprise that a man who has made it his goal to dehumanize and rip apart immigrant families would so brazenly display the racism that drives his policies."

Ocasio-Cortez sent a string of tweets defiantly addressing the president. "You are angry because you can't conceive of an America that includes us," she said. "You rely on a frightened America for your plunder."

Trump's tweets came after House Democrats spent the past week locked in internal tumult over whether Pelosi and House leaders have unfairly marginalized the four liberal freshmen. The firestorm reignited late Friday when the official House Democratic Caucus Twitter account criticized Ocasio-Cortez's chief of staff for suggesting that Democrats had voted to "enable a racist system." And on Saturday, Pressley made comments at the annual Netroots Nation conference that seemed to add to the tension.

Within a few hours on Sunday, Democratic lawmakers were united in defending their colleagues against Trump's attack.

"I've been trying to figure out how to bring everybody together - I think the president just did that for us," Rep. Debbie Dingell, D-Mich., said. "Nobody in our caucus is going to tolerate that kind of hatred."

Dingell, whose suburban Detroit constituency includes one of the largest Muslim American populations of any House district, said Trump's tweet "reinforces the fear of so many people in this country."

Rep. Ruben Gallego, D-Ariz., responded to Trump by recounting how, despite being born in the United States, he was repeatedly told to "go back to Mexico" throughout his life, regardless of his service in the Marine Corps or how well he did in school.

"To people like Trump I will never be American enough," Gallego said in a tweet.

Even lawmakers who have butted heads with the quartet of freshmen stood up for them on Sunday. Rep. Josh Gottheimer, D-N.J., co-chairman of the centrist Problem Solvers Caucus and a frequent critic of the four, said in a tweet that Trump's comments about them were "totally unacceptable and wrong."

By Sunday evening, at least 90 House Democrats, plus Amash, had denounced Trump's remarks, with more than half of them using the words "racist" or "racism" to describe his tweets.

Some Democrats went even further. "This is white nationalism," said Rep. Seth Moulton, D-Mass., who is running for president.

Republican lawmakers, meanwhile, stayed largely silent.

Later Sunday, Trump escalated his attacks on the four lawmakers, tweeting that it was "sad" to see Democrats "sticking up for people who speak so badly of our Country and who, in addition, hate Israel with a true and unbridled passion." The remark appeared to be aimed at Omar, who has previously made comments that some say invoke anti-Semitic stereotypes, and Tlaib, who has advocated for a one-state solution to the Israeli-Palestinian conflict. Trump added that "whenever confronted," the Democratic women "call their adversaries, including Nancy Pelosi, 'RACIST,' " and argued that their remarks "must not be allowed to go unchallenged."

Trump last year sparked an uproar when he reportedly used the term "s---hole" to refer to some countries in Africa and Latin America. He later denied making the remark.

For years, Trump repeatedly raised doubts about President Barack Obama's birth certificate, making the issue part of his 2016 presidential run. He finally acknowledged in September 2016 that Obama was born in the United States - but falsely accused the campaign of Democratic nominee Hillary Clinton of being the source of the rumor.

"Trump is now turning the same birtherism he directed at President Obama against women of color serving in Congress," Rep. Don Beyer, D-Va., said. "Everyone should call this what it is: racism."

Some on Sunday also pointed out the president's family ties to immigrants. Trump's grandparents and mother were born in Europe. His wife, Melania, emigrated from Slovenia to the United States in 1996 for her modeling career, and his first wife, Ivana, was born in what was then Czechoslovakia.

In television appearances, several Trump administration officials declined to defend the president's tweets. They included Ken Cuccinelli, acting director of U.S. Citizenship and Immigration Services, and Mark Morgan, acting commissioner of U.S. Customs and Border Protection.

"I think that you need to talk to the president about his specific tweets," Morgan said on CBS News's "Face the Nation."

Jeh Johnson, who was homeland security secretary during the Obama administration, said on "Face the Nation" that by sending the inflammatory tweets, Trump was undermining his own administration's efforts on a bipartisan immigration reform deal.

“Americans should not become numb to this kind of language and offensive statements,” Johnson said.